(a) Field
The subject matter disclosed generally relates to power supply devices and to methods for analyzing cable communication networks. More particularly, the subject matter relates to switched-mode power supply devices for connection to cable network access devices (outdoor cable network access devices) of cable communication networks and to methods for analyzing the performance of legs of cable communication networks.
(b) Related Prior Art
A power supply device is a device that supplies electric power to an electrical load. The term is most commonly applied to electric power converters that convert one form of electrical energy to another. A regulated power supply is one that controls the output voltage or current to a specific value, the controlled value is held nearly constant despite variations in either load current or the voltage supplied by the power supply's energy source.
Every power supply must obtain the energy it supplies to its load, as well as any energy it consumes while performing that task, from an energy source. Depending on its design, a power supply may obtain energy from electrical energy transmission systems. Common examples of this include power supplies that convert AC line voltage to DC voltage.
A power supply may be implemented as a discrete, stand-alone device or as an integral device that is hardwired to its load.
Commonly specified power supply attributes include, without limitation, the amount of voltage and current it can supply to its load, how stable its output voltage or current is under varying line and load conditions, how long it can supply energy without refueling or recharging (i.e., applies to power supplies that employ portable energy sources), and the like.
Power supplies for electronic devices can be broadly divided into line-frequency (i.e., or “conventional”) and switching power supplies. The line-frequency supply is usually a relatively simple design, but it becomes increasingly bulky and heavy for high-current equipment due to the need for large mains-frequency transformers and heat-sinked electronic regulation circuitry. A switched-mode supply of the same rating as a line-frequency supply will be smaller, is usually more efficient, but would be more complex.
In a switched-mode power supply (i.e., SMPS), the AC mains input is directly rectified and then filtered to obtain a DC voltage. The resulting DC voltage is then switched on and off at a high frequency by electronic switching circuitry, thus producing an AC current that will pass through a high-frequency transformer or inductor. Switching occurs at a very high frequency (i.e., typically 10 kHz-1 MHz), thereby enabling the use of transformers and filter capacitors that are much smaller, lighter, and less expensive than those found in linear power supplies operating at mains frequency. After the inductor or transformer secondary, the high frequency AC is rectified and filtered to produce the DC output voltage. If the SMPS uses an adequately insulated high-frequency transformer, the output will be electrically isolated from the mains; this feature is often essential for safety.
Thus, technicians working on a cable communication network (for example analyzing legs of cable communication networks) usually need to manipulate a plurality of heavy instruments and a lot of materials when they climb in electrical posts at heights of 25 foot and over. The technicians furthermore often need to stay up in the air while taking some measurements on the cable communication network as such equipment cannot remain about an outdoor cable network access device by its own. This can result in non-productive operations and injuries.
Furthermore, the power supplies required on cable communication networks become increasingly bulky and heavy for high-current equipment due to the need for large mains-frequency transformers and heat-sinked electronic regulation circuitry.
There is therefore a need for improved switched-mode power supply devices to overcome the prior art disadvantages and for improved methods of analyzing legs of cable communication networks.